Data storage/retrieval devices such as disk drives are well known in the industry. Disk drives store or retrieve digital data on a plurality of circular, concentric data tracks on the surfaces of a rigid data storage disk. The disk is typically mounted for rotation on the hub of a spindle motor. In disk drives of the current generation, the spindle motor can rotate the disk at speeds of up to 10,000 RPM.
Data is stored to or retrieved from the disk by an actuator that is controllably moved. The actuator typically includes of an electromagnetic transducer head carried on an actuator assembly. The actuator assembly moves the head from track to track and has assumed many forms historically, with most disk drives of the current generation incorporating an actuator assembly of the type referred to as a rotary voice coil actuator assembly. A typical rotary voice coil actuator assembly includes of a pivot pin fixedly attached to a disk drive base member. The pivot pin is mounted such that its central axis is normal to the plane of rotation of the disk. An actuator assembly frame can be mounted to the pivot pin by an arrangement of precision ball bearing assemblies, and supports a coil which is suspended in the magnetic field of an array of permanent magnets, which are fixedly mounted to the drive base member. When controlled DC current is applied to the coil, a magnetic field is formed surrounding the coil that interacts with the magnetic field of the permanent magnets to rotate the actuator assembly in accordance with the well-known Lorentz relationship.
As the actuator assembly rotates about the pivot pin, the head is moved across the data tracks along an arcuate path. If the pivot pin is not properly attached to the disk drive base member, the distance between the head and the data storage disk may vary as the actuator assembly moves along the arcuate path.
Disclosed is a method for aligning a rotating device such as an actuator assembly to a base of, for example, a disk drive. The device is rotatably mounted to the base about the pivot pin. The method may involve adjusting the angular position of the pivot pin relative to the base unless or until the actuator assembly rotates in a first plane parallel to a second plane containing a surface of the data storage disk.
In one embodiment, the data storage disk is mounted for rotation on a disk rotation motor. The disk rotation motor, in turn, is mounted to a base. With the device positioned between the base and the data storage disk, the device is rotated about the pivot pin. While the device is rotated about the pivot pin, electrical current is provided to the device. The magnitude of the electrical current is proportional or inversely proportional to a distance D separating the device from the data storage disk. The electrical current is monitored as the device rotates about the pivot pin. When the monitored current is constant in magnitude as the device rotates about the pivot pin, the angle between the device and the base is such that the device should rotate in the first plane.
In another embodiment the data storage disk is illuminated with light as the device rotates about the pivot pin. Light reflected from the data storage disk is detected. Signals corresponding to the detected light are generated as the device rotates about the pivot pin. These signals are monitored. When the monitored signals are constant in magnitude as the device rotates about the pivot pin, the angle between the device and the base is such that the device should rotate in the first plane.